1. Field of the Invention
The invention relates to a method for beamforming training, and more particularly to a method for beamforming training a trainee communications device with one or more trainer communications devices in a communications system.
2. Description of the Related Art
Beamforming techniques that use multiple antennas at both the transmitter and receiver ends may be applied in a communications system to improve communications performance. Generally, the communications devices employing multiple antennas need to be trained in order to obtain optimum Tx and/or Rx antenna configurations before data transmission. For a conventional beamforming training procedure, a communications device transmits one or more predetermined beamforming training bit-sequences to a peer communications device via a one-to-one training procedure. Particularly, for high frequency applications, such as a millimeter wave communications system, it is preferable that only one communications device be trained during a training session due to directionality of the antenna.
Based on the conventional beamforming training method, when there are more than one communications device in a communications system, a great number, which amounts to the square of the number of communications devices, of sessions and messages are required for the training procedure. For communications devices to exchange data over an asymmetrical channel with asymmetrical configurations, the amount of training sessions and messages are quadrupled in order to establish a bi-directional communications path, which seriously degrades training efficiency. Thus, a novel beamforming training method that is able to solve the foregoing inefficiencies is highly required.